Scott Delaney Project Summary / Abstract Childhood poverty is a known risk factor for the development of aggressive behavior problems in youth, but pathways linking poverty exposure to aggression remain unclear. Understanding this relationship is complicated by poverty?s complex ecology of biological, social, and psychosocial exposures. Nevertheless, emerging research suggests physically threatening experiences are particularly salient to the development of aggressive behavior problems among disadvantaged children. Efforts to identify biological mechanisms linking early-life threat exposure to aggressive behavior have pointed to alterations in brain biology. Cross-sectional, observational neuroimaging studies have linked early-life low family income exposure to changes in brain morphology within the corticolimbic system of the brain, which is involved in both threat perception and aggressive behavior. However, neuroimaging studies to date have treated poverty and low family income as a monolithic experience, and they do not assess the specific role of threatening experiences on corticolimbic development. Moreover, most neuroimaging studies of childhood poverty rely on cross-sectional measures of brain development, thereby rendering them insufficient to support causal inferences. Using longitudinal data from the Generation R birth cohort, the proposed research aims to explore the relationships between childhood exposure to threatening experiences, structural brain changes, and aggressive behavior. Specifically, the research first aims to assess associations between (1) early-life threat exposure and corticolimbic alterations, and (2) corticolimbic alterations and aggressive behavior. Thereafter, the research aims to assess whether and to what extent (1) corticolimbic alterations mediate the relationship between threat exposure and aggressive behavior, and (2) child biological sex, parental education, and timing of threat exposure moderate the relationships of interest. These analyses are made possible by the magnitude of the Generation R study, which contains life-long social exposure data, life-long behavioral phenotypic data, and MRI scans from multiple time points for nearly 4000 participants. This fellowship application has two long-term objectives. First, the application proposes research that will contribute to literature on child brain development, which in turn may be used to inform public health policy and practice by guiding the development of early childhood interventions designed to mitigate the toxic effects of social disadvantage. Second, this proposal?s research training plan is designed to support the applicant?s mentored development toward interdisciplinary, independent research, and to enable additional, more advanced training in social and child psychiatric epidemiology, developmental neuroscience, and biostatistics.